\documentclass{article}


\usepackage{tikz}

\usetikzlibrary{arrows,snakes,backgrounds}


\begin{document}

is a chromosome
comprised of seven genes:\\

\begin{tikzpicture}
\draw (-4,0) node[minimum size=1cm,draw] {p};
\draw (-3,0) node[minimum size=1cm,draw] {X};
\draw (-2,0) node[minimum size=1cm,draw] {Y};
\draw (-1,0) node[minimum size=1cm,draw] {r};
\draw (0,0) node[minimum size=1cm,draw] {X};
\draw (1,0) node[minimum size=1cm,draw] {12};
\draw (2,0) node[minimum size=1cm,draw] {a};
\end{tikzpicture}



\bigskip \bigskip \bigskip \bigskip

...will enlarge it. This is shown as follows:\\

\begin{tikzpicture}
\draw (-4,0) node[minimum size=1cm,draw] {p};
\draw (-3,0) node[minimum size=1cm,draw] {X};
\draw (-2,0) node[minimum size=1cm,draw] {Y};
\draw (-1,0) node[minimum size=1cm,draw ] {r};
\draw (0,0) node[minimum size=1cm,draw] {X};
\draw (1,0) node[minimum size=1cm,draw, fill =green!50] {12.3};
\draw (2,0) node[minimum size=1cm,draw] {q};
\draw (3,0) node[minimum size=1cm,draw] {Y};


\draw[->>, line width=1.5pt, color=orange] (1,-0.5) -- (1,-1.5);

\draw (-4.45,-2) node[minimum size=1cm,draw] {p};
\draw (-3.45,-2) node[minimum size=1cm,draw] {X};
\draw (-2.45,-2) node[minimum size=1cm,draw] {Y};
\draw (-1.45,-2) node[minimum size=1cm,draw] {r};
\draw (-0.45,-2) node[minimum size=1cm,draw] {X};
\draw (1.1,-2) node[minimum size=1cm,draw, fill =green!50] {$\left[12.3..6.5\right]$};
\draw (2.6,-2) node[minimum size=1cm,draw] {q};
\draw (3.6,-2) node[minimum size=1cm,draw] {Y};
\end{tikzpicture}

\bigskip \bigskip \bigskip \bigskip


then one value
is added, for example:\\

\begin{tikzpicture}
\draw (-4,0) node[minimum size=1cm,draw] {p};
\draw (-3,0) node[minimum size=1cm,draw] {X};
\draw (-2,0) node[minimum size=1cm,draw] {Y};
\draw (-1,0) node[minimum size=1cm,draw ] {r};
\draw (0,0) node[minimum size=1cm,draw] {X};
\draw (1,0) node[minimum size=1cm,draw, fill =green!50] {blue};
\draw (2,0) node[minimum size=1cm,draw] {q};
\draw (3,0) node[minimum size=1cm,draw] {Y};


\draw[->>, line width=1.5pt, color=orange] (1,-0.5) -- (1,-1.5);

\draw (-4.45,-2) node[minimum size=1cm,draw] {p};
\draw (-3.45,-2) node[minimum size=1cm,draw] {X};
\draw (-2.45,-2) node[minimum size=1cm,draw] {Y};
\draw (-1.45,-2) node[minimum size=1cm,draw] {r};
\draw (-0.45,-2) node[minimum size=1cm,draw] {X};
\draw (1.1,-2) node[minimum size=1cm,draw, fill =green!50] {$\left[blue,white\right]$};
\draw (2.6,-2) node[minimum size=1cm,draw] {q};
\draw (3.6,-2) node[minimum size=1cm,draw] {Y};
\end{tikzpicture}









\bigskip
\bigskip
\bigskip
\bigskip
\bigskip



\begin{tikzpicture}
\draw (-3,0) node[minimum size=1cm,draw] {$L_0$};
\draw (-1.5,0) node[minimum size=1cm,draw] {$L_1$};
\draw (0,0) node[minimum size=1cm,draw] {$L_2$};
\draw (1.5,0) node[minimum size=1cm,draw] {$\ldots$};
\draw (3,0) node[minimum size=1cm,draw] {$L_n$};
\end{tikzpicture}





\bigskip
\bigskip
\bigskip
\bigskip
\bigskip







\begin{tikzpicture}
\draw (-4.4,0) node[minimum size=1cm,draw] {p};
\draw (-3.4,0) node[minimum size=1cm,draw] {X};
\draw (-2.4,0) node[minimum size=1cm,draw] {Y};
\draw (-1.4,0) node[minimum size=1cm,draw ] {r};
\draw (-0.4,0) node[minimum size=1cm,draw] {X};
\draw (1.1,0) node[minimum size=1cm,draw, fill =green!50] {$\left[12.3 .. 19.5\right]$};
\draw (2.6,0) node[minimum size=1cm,draw] {q};
\draw (3.6,0) node[minimum size=1cm,draw] {Y};


\draw[<->, line width=1.5pt, color=orange] (1,-0.5) -- (1,-1.5);

\draw (-4.45,-2) node[minimum size=1cm,draw] {p};
\draw (-3.45,-2) node[minimum size=1cm,draw] {X};
\draw (-2.45,-2) node[minimum size=1cm,draw] {Y};
\draw (-1.45,-2) node[minimum size=1cm,draw] {r};
\draw (-0.45,-2) node[minimum size=1cm,draw] {X};
\draw (1.1,-2) node[minimum size=1cm,draw, fill =green!50] {$\left[25.7 .. 31.2\right]$};
\draw (2.6,-2) node[minimum size=1cm,draw] {q};
\draw (3.6,-2) node[minimum size=1cm,draw] {Y};
\end{tikzpicture}


\end{document}